Article Date: 5/1/2001

Multifocals
Meeting the Multifocal Challenge 
Experts answer common questions about multifocal lenses.
By Terri B. Goshko,  Senior Associate Editor

Is the task of fitting multifocal contact lenses challenging to you? Are you feeling confident about how to choose the best multifocal lens for your patients?

This month, we'll give you some fitting and problem-solving tips from experts, as well as other timely information that you may find helpful for this aspect of your practice.

The following is good advice from two well-known contact lens experts.

QUESTION: When are soft multifocals more appropriate than rigid gas permeable (RGP) lenses?

Dr. Stiegemeier: If the refractive cylinder is less than 1.00D, or the spherical component is at least three times the cylindrical component, I'll try a soft multifocal. If the refractive cylinder is moderate to high, I'll try an RGP multifocal lens.

I tend to fit patients in multifocals in the same type lens they wore before their multifocal fit. One exception is patients wearing soft torics -- I'll try to switch them into RGP multifocals. If they can't tolerate them, or have had a prior negative impression of rigid lenses, I'll fit some of the new toric multifocals that have worked very well.

Dr. Szczotka: Soft lenses are appropriate only if the patient is a candidate for nontoric distance soft contact lenses (i.e., low astigmatism, previous soft lens wearer). If the patient's a candidate for either soft or RGP lenses, soft lenses are favored over RGPs for those who desire only part-time or social contact lens wear because RGP adaptation isn't an issue then.

Some new, nondisposable specialty toric soft multifocal lenses available would be suitable for patients who're RGP intolerant or have lenticular astigmatism necessitating a soft toric lens for vision correction, with a built-in aspheric multifocal. Consider these lenses for specialty cases when you've ruled out a standard soft multifocal or RGP lens.

Survey Says . . .

The demand for soft multifocal contact lenses is on the rise.

In CIBA Vision's recent e-mail survey of more than 500 U.S. eyecare professionals, 75% of respondents reported increasing patient demand for soft bifocal or multifocal contact lenses. And the challenges of fitting are being met, too -- 64% of respondents reported fitting success of 50% or greater.

Richard E. Weisbarth, O.D., F.A.A.O., CIBA Vision's executive director of professional services for North America says, "The success rates with soft multifocal contact lenses are increasing as newer products become more accepted . . . we advocate that practitioners start with soft multifocals before settling on the compromise of monovision. Not only do multifocals preserve binocularity, but they also offer higher value to patients."

For fitting presbyopes, 27% of respondents most often chose bifocal/multifocal contact lenses; 54% used monovision. Fifteen percent said they most often fit presbyopes with single-vision contact lenses and reading glasses, while 9% most commonly used rigid gas permeable contact lenses for these patients.

Same-day dispensing of contact lenses for presbyopic patients was important, according to 80% of eyecare professionals.

Most of my bifocal contact lens fits are with RGP multifocal lenses. They have the advantage of allowing full correction of corneal astigmatism, and variable back surface eccentricities which allow various add powers. Any person who has been wearing RGP lenses or any new presbyope who's an RGP candidate and wants to wear contact lenses for most of the time is a good candidate for RGP multifocal lenses.

I usually use simultaneous back surface aspheric designs, but an alternating/translating design is also available. This design has higher add powers for the mature presbyope, but has no intermediate range of focus and may have variable vision if the add segment moves into the visual axis with each blink. Trifocal segmented designs exist, but I haven't found them to work.

QUESTION: Do you need to have trial fitting sets?

Dr. Stiegemeier: They're essential for all soft lens multifocal fits and most RGP multifocal fits. They're not only helpful for final lens parameters, but they can help you weed out patients who can't cortically adapt. They also help you capture patients while their enthusiasm is at its peak. "Show, then tell" works well with trial lenses; I believe much of my success with soft multifocals is due to trial sets.

You can fit RGP multifocals without trial lenses, but it's helpful to have them, especially when fitting translating rigid multifocals. I like to demonstrate to the patient how the lens will feel, and what type of vision he can expect. I also like to evaluate the lens on the eye to check fluorescein patterns and bifocal height. I recommend that you try several types of simultaneous and translating RGPs and then invest in fitting sets of the types you're most successful with.

Dr. Szczotka: You should fit all soft lens multifocals from trial lens sets -- that's the beauty of the new disposable lens systems. The fitting sets allow on-site fitting and problem solving. Remember, fitting these patients is both an art and a science. Often, we have to find the best compromise that fits a patient's lifestyle, and there isn't one lens per patient that we can extract from a manufacturer's nomogram.

However, I have increasingly good success rates using empirical RGP lens ordering based on topography or keratometry plus manifest refraction. Although fitting from a diagnostic lens set will ultimately give you the best success rate, I don't hesitate to try empirical ordering, knowing that a lens is warranted for exchange and that my patient understands that a reorder may sometimes be necessary.

QUESTION: Do you think that there's a role for modified monovision with multifocals?

Dr. Stiegemeier: Yes, when performed with the appropriate lens design. Multifocals should give good vision for at least two focal points binocularly. In early presbyopia, or for patients who require excellent distance acuity, a bifocal lens (usually on the nondominant eye) with a single vision distance lens (usually on the dominant eye) works. Patients needing excellent near acuity may combine a bifocal lens (on the dominant eye) with a single vision near lens (on the nondominant eye).

There's also a "Modified Bifocal Approach" where two bifocal lenses are used -- one lens (on the dominant eye) is set for distance acuity and the other lens (on the nondominant eye) is set for intermediate and near.

Some soft lens designs are made to use this technique as a complementary system. You can use some -- but not all -- disposables this way. This technique also works with RGP designs. Demonstrate the technique by using a loose plus trial lens over one eye to see whether "weighting" the prescription on one eye significantly improves or hampers vision. It's also a useful trial that can help tell you whether the patient can adapt.

Dr. Szczotka: Yes, I think there's a role for monovision with bifocals, especially for simultaneous progressive soft or RGP lenses when near vision is compromised and/or additional add power isn't an option.

For example, increased add power may not be available (the manufacturer may not offer it, or the increased add power may sometimes diminish your patient's distance vision).

I tell the patient she's still wearing bifocals but that one lens (usually on the dominant eye) will cover distance and intermediate vision and the other lens will cover intermediate and near. It works for many patients.

Although I don't recommend it as the primary fitting option, I sometimes end with it. In a successful patient, the nondominant eye (near) still has at least 20/40 distance vision and 20/20 near.

QUESTION: Which lenses are best for which situations (e.g., cosmetic use, computers, etc.)?

Dr. Stiegemeier: For patients who need outstanding acuity both distance and near and wear or have worn RGPs, I opt for the RGP translating designs. If the patient currently wears RGP lenses, is an early presbyope, 

 

An Alternative to LASIK
By Alan N. Glazier, O.D., F.A.A.O.

 

A good opportunity to offer bifocal contact lenses arises during laser-assisted in situ keratomileusis (LASIK) consultation. For example: A presbyopic patient learns during consultation that she'll no longer be able to remove her glasses to see at near after the surgery. If I see she's disappointed or she tells me she's no longer interested in LASIK, I say "let's explore a better alternative for 'over-40' vision. Bifocal contact lenses can provide you with the 'glasses-free' vision you seek." Because the LASIK candidate is open to new technology, and there's significantly less risk and cost, she'll often decide to try bifocal contacts first, or instead of LASIK.

Most of my patients have either never heard of bifocal contact lenses or believed that they didn't work well. It's important to build realistic expectations, exceed them and thus build patient trust and confidence. Bifocal contact lenses provide a more profitable, longer-term revenue stream than LASIK would, while meeting patients' needs. A happy bifocal contact lens patient is a great referral source.

has a lower lid lower than the inferior limbus, or has intermediate vision needs, I'll opt for an RGP simultaneous vision design.

If the patient is intolerant of RGPs or has worn soft lenses, I start with a simultaneous design soft disposable lens. For all new patients who require a multifocal design and can wear soft lenses, I begin with soft disposable multifocals. I also use soft disposable multifocals for patients who require excellent intermediate acuity, such as those who work on computers. Disposable multifocals are also my choice for patients who want flexibility, such as part-time or extended wear.

Dr. Szczotka: First, you need to have a general knowledge of a prescribed lens's design. If the patient requires any intermediate vision (most do, for computer use or car dashboard, for example), a progressive or simultaneous contact lens is best. Most concentric simultaneous lenses are divided into either a center-distance or a near-distance design, which refers to the optics in the lens center.

Most RGP bifocals are center distance and have a progressive shift to more plus power in the lens periphery. A center distance lens is best suited for patients who need excellent distance vision under bright or average light. The patient will have better near vision when her pupils are larger. Therefore, the center distance lenses will work if, for example, a woman wants to wear them to read a menu in a dimly lit restaurant. RGP center distance lenses also have mild lens translation in downgaze, which can enhance near vision under all lighting conditions.

Soft lenses are available as center distance or center near. Center near works best for patients who need excellent near vision under bright light (such as in brightly lit offices). When the patient's pupil constricts, near vision is enhanced and distance vision is diminished. Distance vision improves under dim light as the pupil dilates and the distance optics enter the visual axis.

Concentric simultaneous soft lenses with alternating optics are also available. They're pupil independent; therefore, changes in room illumination are less of a concern with them.

Another form of modified monovision with soft lenses is to use a center-distance lens on one eye (usually the dominant eye) and a center-near lens on the other eye. This gives monocularly enhanced vision at a particular distance while preserving binocularity. It works well for those previous monovision patients who want to upgrade to bifocals. 

Dr. Stiegemeier is in private practice in Beachwood, Ohio. Dr. Szczotka is an assistant professor at Case Western Reserve University Department of Ophthalmology and director of the contact lens service at University Hospitals of Cleveland in Ohio.

 

The Bifocal Problem-Solver
BY ALAN N. GLAZIER, O.D., F.A.A.O., Rockville, Md.

Selecting the proper parameters and encouraging realistic patient expectations are vital when fitting bifocal contact lenses. We've all read about fitting "mono-style" bifocal contact lenses (modified monovision or unequal add powers), and contact lens manufacturers have urged us to explain to patients that it may be necessary to use a low-power reading lens over bifocal contact lenses when extended near work is necessary.

However, what about the other problems our patients may experience while trying bifocal contact lenses in their first few weeks of fitting? How can we help our patients deal with them? Below are some problems I often see and suggestions I've found useful in solving them.

Battling the demons

Common complaints your patients might voice include the following:

  • "Doc, my vision is worse at night." Almost all bifocal contact lens wearers, whether using rigid gas permeable or soft lenses, will complain of poor vision at night. Before dispensing the lenses, make sure your patient is aware of this.
    I like to tell my patient, "During the trial fitting, you'll experience worse vision at night than during the day. When the fitting's finished, we'll fit you with a pair of eyeglasses for when you need improved vision at night. You may use them while driving at night or at the movies, and not have to remove your contact lenses."
    This reassures the patient, and the sale of eyeglasses, frames and anti-reflective coating yields additional revenue for the practice.
  • "Doc, something's wrong -- one eye is blurry." During an initial fit, I'll request that when the patient leaves my office, she not test each eye individually. I explain that unlike distance contact lenses, with which both eyes should see alike, bifocal contacts are designed to work only as a pair. If they're used individually, one eye will always see worse than the other.
    Testing each eye individually can fool patients, making them think that something's wrong with what you prescribed. By having them agree not to do their own monocular acuity testing, you'll increase your fitting success.
  • "Doc, why have I had to come in so many times for this fitting?" Probably, most of you preface your fitting by telling the patient that multiple follow-up visits may be necessary. But no matter how well you present the information, patients may still lose confidence if they have to return more than twice.
    I explain that when fitting distance contact lenses, doctors "juggle" only three prescriptions: the right eye, the left eye and both eyes together. I then say that when fitting the bifocal lens, we must juggle six prescriptions:

1. the right eye distance
2. the right eye near
3. the left eye distance
4. the left eye near
5. both eyes together, distance
6. both eyes together, near.

This helps explain the complexity of the fit. It also helps the patient understand that the bifocal lens is a specialty lens, and the additional costs of fitting specialty lenses are justified.

Taking a little time for explaining and reassuring is worth its weight in gold. Try it -- you might be surprised at how well it works.

Dr. Glazier is in private practice in Rockville, Md. He has several patents in contact lens technology and is CEO of Eye-O-Tech, Inc., an eyecare research and development company. You can visit his virtual practice on the Web at www.youreyesite.com.



Optometric Management, Issue: May 2001